Preparation method of high-density low-resistivity ZTO target material

Abstract

The invention relates to the technical field of target materials, in particular to a preparation method of a high-density low-resistivity ZTO target material, which adopts nanoscale raw material powder to enhance sintering activity, reduce densification temperature and reduce defect formation; cerium oxide and titanium oxide optimize a grain boundary structure, and synergism of low resistivity and high densification is achieved; sanding to a submicron level to ensure that the components are highly dispersed; the special dispersing agent and the defoaming agent are added, so that agglomeration is avoided; the gradient density is eliminated through two times of static pressure, the blank density is increased by more than 15%, sintering shrinkage deformation is reduced, organic matter is efficiently removed in the three sintering stages, SnO2 reduction volatilization is inhibited, grain boundary diffusion is promoted, and a nearly-fully-compact structure is achieved; and finally, cooling to 800 DEG C, preserving heat for 10 hours, releasing residual stress, and avoiding cracking. And finally, the high-density and low-resistivity ZTO target material is prepared, the prepared target material is excellent in performance and low in cost, and the application requirements in the fields of electronic display, thin-film solar cells and the like are met.

Description

Technical Field

[0001] The present invention relates to the technical field of target materials, and in particular to a method for preparing a high-density and low-resistivity ZTO target material. Background Art

[0002] Traditional indium-based targets (such as ITO targets) are facing problems such as scarcity of indium resources and high prices, prompting researchers to develop indium-free targets as an alternative. Traditional ITO targets rely on scarce indium (In), which is costly and unsustainable. ZTO targets have problems such as low density and high resistivity. The low density causes particle splashing during sputtering, and the high resistivity affects the conductivity of the film. Conventional sintering processes easily lead to Zn / Sn component segregation, affecting the uniformity of the film. Therefore, a method for preparing ZTO targets is needed to ensure high density and low resistivity to ensure the uniformity of the film. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a method for preparing a high-density and low-resistivity ZTO target material, which solves the problems in the background technology.

[0004] Based on the above objectives, the present invention provides a method for preparing a high-density, low-resistivity ZTO target, comprising the following steps:

[0005] Step 1, weighing raw materials: weighing raw material powders according to the following mass percentages: zinc oxide 78-82%, tin oxide 15-20%, cerium oxide 0-2%, titanium oxide 0-2%;

[0006] Step 2, slurry sand grinding: add the above powder to a powder mixer, then add deionized water to mix the powder, add the mixed powder to a sand grinder, and sand grind with 0.1mm zirconium oxide beads to obtain a slurry particle size of D10≤0.1μm, D50≤0.2μm, and D90≤0.9μm;

[0007] Step 3, powder granulation: After the sand-milled slurry reaches the required particle size, it is granulated by a high-temperature spray granulator;

[0008] Step 4: Cold pressing: Place the granulated powder into a 4-inch flat target mold and use a hydraulic press to perform two pressure moldings to obtain a target embryo;

[0009] Step 5, target sintering: Place the formed target blank into a sintering furnace and sinter in three stages. In the first stage, the temperature is raised from room temperature to 650°C at a heating rate of 0.5-2°C / min for dehydration and degreasing; in the second stage, the temperature is raised from 650°C to 1000°C at a heating rate of 3-6°C / min; in the third stage, the temperature is raised from 1000°C to 1500°C at a heating rate of 4-8°C / min for hot isostatic pressing sintering, kept warm for 10 hours, and finally cooled to 800°C to obtain the target.

[0010] Preferably, the raw material powders in step 1 are all nano-scale powders with a powder particle size of 100 nm to 500 nm.

[0011] Preferably, in the step 2, the amount of deionized water added is 30-50% of the total mass of the powder; the sand mill rotates at a speed of 2000-3000 r / min, the grinding is performed 3-5 times, and the grinding time is 5-10 h.

[0012] Preferably, in the sand grinding process of step 2, 0.1% to 0.6% by mass of dispersant BLJ-3359, 1% to 5% by mass of binders BD25 and BD20, and 0.05% to 0.1% by mass of defoamer MOK-6026 are added.

[0013] Preferably, the high-temperature spray granulator for powder granulation in step 3 has an air inlet temperature of 190-240° C., an air outlet temperature of 90-130° C., and a granulation rotation speed of 7000-9000 r / min.

[0014] Preferably, in the step 4, the molding pressure of the first cold pressing molding is 100-200 MPa, and the molding time is 5-10 minutes. The flat target formed for the first time is vacuumed by a vacuum machine and then placed in a cold isostatic pressing mold for the second pressure molding. The molding pressure of the second pressure molding is 180-210 MPa, and the molding time is 40-60 minutes.

[0015] Preferably, in the first sintering stage of step five, air is passed through during the process of heating from room temperature to 650°C.

[0016] Preferably, during the second stage of step five, oxygen is introduced during the process of heating from 650° C. to 1000° C., with an oxygen flow rate of 10 L / min.

[0017] Preferably, in the third stage of step five, argon is passed during the process of heating from 1000°C to -1500°C and cooling to 800°C, and hot isostatic pressing sintering is carried out in an argon atmosphere of 100-150 MPa for 20 hours and the temperature is kept for 10 hours.

[0018] The beneficial effects of the present invention are as follows: the present invention adopts nano-scale raw material powder to enhance sintering activity, lower densification temperature, and reduce defect formation; cerium oxide and titanium oxide optimize the grain boundary structure to achieve synergy between low resistivity and high densification; sand grinding to submicron level ensures high dispersion of components; and special dispersants and defoaming agents are added to avoid agglomeration.

[0019] The spray granulation air inlet temperature is 190-240℃ and the rotation speed is 7000-9000rpm, forming spherical particles with good fluidity and improving the uniformity of subsequent pressing; pre-forming is first performed by mechanical pressing at 100-200MPa, and then cold isostatic pressing is performed at 180-210MPa to eliminate gradient density, increasing the green body density by more than 15% and reducing sintering shrinkage and deformation.

[0020] The first sintering stage is debinding: heating from room temperature to 650°C in an air environment to efficiently remove organic matter. The second stage is pre-sintering: heating from 650°C to 1000°C in an oxygen atmosphere to inhibit the reduction and volatilization of SnO2. The third stage is final sintering: hot isostatic pressing from 1000 to 1500°C in an argon atmosphere at 100–150 MPa promotes grain boundary diffusion, eliminating >99% of closed pores and achieving a nearly fully dense structure. Finally, the temperature is lowered to 800°C and held for 10 hours to release residual stress and prevent cracking. The result is a high-density, low-resistivity ZTO target material, offering excellent performance and low cost, meeting the application needs of electronic displays, thin-film solar cells, and other fields. DETAILED DESCRIPTION

[0021] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to specific embodiments.

[0022] It should be noted that, unless otherwise defined, the technical or scientific terms used in the present invention should have the usual meanings understood by people with ordinary skills in the field to which the present invention belongs. The "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0023] A method for preparing a high-density, low-resistivity ZTO target material comprises the following steps:

[0024] S1. Weighing raw materials: Weighing raw material powders of nano-scale zinc oxide, tin oxide, cerium oxide, and titanium oxide with a particle size of 100 nm to 500 nm according to the formula of Examples 1-4; by using nano-scale raw material powders, sintering activity is enhanced, densification temperature is lowered, and defect formation is reduced; cerium oxide and titanium oxide optimize the grain boundary structure to achieve synergistic low resistivity and high densification;

[0025] S2, slurry sand milling: add the above powder to a powder mixer, then add deionized water in an amount of 30-50% of the total mass of the powder to mix the powder, and then add the mixed powder to a sand mill. Sand milling is performed using 0.1mm zirconium oxide beads, the sand mill speed is 33000r / min, the grinding is performed 5 times, and the grinding time is 10h. Add 0.5% by mass of dispersant BLJ-3359, 3% by mass of binders BD25 and BD20, and 0.1% by mass of defoamer MOK-602; sand milling obtains a slurry particle size of D10≤0.1μm, D50≤0.2μm, and D90≤0.9μm; sand milling is performed to submicron level to ensure that the components are highly dispersed; special dispersants and defoamers are added to avoid agglomeration;

[0026] S3, powder granulation: After the sand-milled slurry reaches the particle size requirement, it is granulated by a high-temperature spray granulator. The inlet temperature of the high-temperature spray granulator is 240°C, the outlet temperature is 130°C, and the granulation speed is 9000r / min. Spherical particles with good fluidity are formed to improve the uniformity of subsequent pressing.

[0027] S4, first cold pressing: the granulated powder is placed into a 4-inch flat target mold and the first molding is performed using a hydraulic press at a molding pressure of 200 MPa for 10 minutes. The flat target packaged in a PE film bag is vacuumed using a vacuum machine and then placed into a cold isostatic pressing mold.

[0028] S5, performing a second pressure forming process, wherein the forming pressure of the second pressure forming process is 210 MPa and the forming time is 60 minutes; the gradient density is eliminated, the green body density is increased, and the sintering shrinkage deformation is reduced;

[0029] S6, target sintering: the formed target body is placed in a sintering furnace and sintered in three stages;

[0030] In the first stage, the temperature was raised from room temperature to 650°C at a heating rate of 2°C / min in an air atmosphere for dehydration and degreasing;

[0031] In the second stage, the temperature was raised from 650°C to 1000°C at a heating rate of 5°C / min in an oxygen atmosphere to inhibit the reduction and volatilization of SnO2;

[0032] In the third stage, the temperature was raised from 1000°C to 1500°C at 6°C / min in an argon atmosphere for hot isostatic pressing and sintering for 20 hours to promote grain boundary diffusion, and the closed hole elimination rate was greater than 99%. Finally, the temperature was lowered to 800°C and kept for 10 hours to release residual stress and avoid cracking, thereby obtaining the target material.

[0033] The raw material powder formula, relative density and resistivity of Examples 1-4 are as follows -6

[0034] Zinc oxide wt% Tin oxide wt% Cerium oxide wt% Titanium oxide / % Relative density / % Resistivity / (Ω·cm) Example 1 80 19 1 88.8％ <![CDATA[1.0×10 -6 ]]> Example 2 83 15 2 98.1％ <![CDATA[1.0×10 -3 ]]> Example 3 80 19 1 99.8％ <![CDATA[4.0×10 -4 ]]> Example 4 83 15 2 98.0％ <![CDATA[2.0×10 -3 ]]>

[0035] It can be seen from the above table that adding only a small amount of cerium oxide does not significantly improve the relative density and resistivity, while adding a small amount of titanium oxide significantly improves the relative density and resistivity.

[0036] Those skilled in the art will understand that the discussion of any of the above embodiments is merely illustrative and is not intended to limit the scope of the present invention to these examples. Within the spirit and principles of the present invention, the technical features of the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and many other variations exist in the various aspects of the present invention described above, which are not provided in detail for the sake of clarity. Any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing a high-density, low-resistivity ZTO target, characterized in that: The following steps are included: Step 1, weighing raw materials: weighing raw material powders according to the following mass percentages: zinc oxide 78-82%, tin oxide 15-20%, cerium oxide 0-2%, titanium oxide 0-2%; Step 2, slurry sand grinding: add the above powder to a powder mixer, then add deionized water to mix the powder, add the mixed powder to a sand grinder, and sand grind with 0.1mm zirconium oxide beads to obtain a slurry particle size of D10≤0.1μm, D50≤0.2μm, and D90≤0.9μm; Step 3, powder granulation: After the sand-milled slurry reaches the required particle size, it is granulated by a high-temperature spray granulator; Step 4: Cold pressing: Place the granulated powder into a 4-inch flat target mold and use a hydraulic press to perform two pressure moldings to obtain a target embryo; Step 5, target sintering: Place the formed target blank into a sintering furnace and sinter in three stages. In the first stage, the temperature is raised from room temperature to 650°C at a heating rate of 0.5-2°C / min for dehydration and degreasing; in the second stage, the temperature is raised from 650°C to 1000°C at a heating rate of 3-6°C / min; in the third stage, the temperature is raised from 1000°C to 1500°C at a heating rate of 4-8°C / min for hot isostatic pressing sintering, kept warm for 10 hours, and finally cooled to 800°C to obtain the target.

2. The method for preparing a high-density, low-resistivity ZTO target according to claim 1, characterized in that: The raw material powders in step 1 are all nano-scale powders with a powder particle size of 100nm to 500nm.

3. The method for preparing a high-density, low-resistivity ZTO target according to claim 1, characterized in that: In the step 2, the amount of deionized water added is 30-50% of the total mass of the powder; the speed of the sand mill is 2000-3000 r / min, the grinding is 3-5 times, and the grinding time is 5-10 hours.

4. The method for preparing a high-density, low-resistivity ZTO target according to claim 3, characterized in that: In the sand grinding process of step 2, 0.1% to 0.6% by mass of dispersant BLJ-3359, 1% to 5% by mass of binders BD25 and BD20, and 0.05% to 0.1% by mass of defoamer MOK-6026 are added.

5. The method for preparing a high-density, low-resistivity ZTO target according to claim 1, wherein: The high-temperature spray granulator for powder granulation in step 3 has an air inlet temperature of 190-240° C., an air outlet temperature of 90-130° C., and a granulation speed of 7000-9000 r / min.

6. The method for preparing a high-density, low-resistivity ZTO target according to claim 1, characterized in that: In the fourth step, the first pressure molding of the cold pressing process has a molding pressure of 100-200 MPa and a molding time of 5-10 minutes. The flat target formed for the first time is vacuumed by a vacuum machine and then placed in a cold isostatic pressing mold for a second pressure molding. The molding pressure of the second pressure molding is 180-210 MPa and the molding time is 40-60 minutes.

7. The method for preparing a high-density, low-resistivity ZTO target according to claim 1, characterized in that: In the first stage of sintering in step five, air is passed through during the process of heating from room temperature to 650° C.

8. The method for preparing a high-density, low-resistivity ZTO target according to claim 7, characterized in that: In the second stage of step 5, oxygen is introduced during the process of heating from 650° C. to 1000° C., with an oxygen flow rate of 10 L / min.

9. The method for preparing a high-density, low-resistivity ZTO target according to claim 8, characterized in that: In the third stage of step five, argon is passed through during the process of heating from 1000°C to -1500°C and cooling to 800°C, and hot isostatic pressing sintering is carried out in an argon atmosphere of 100-150 MPa for 20 hours and the temperature is kept for 10 hours.